Iron Flashcards
ferric form
fe3+
ferrous form
fe2+
where does fe2+ sit in haemoglobin
in prophyrin ring
where is the majority of body iron found
in haem
wjere does iron absorption mainly occur
duodenum
what is iron absorption enhanced by
aacorbic acid- vit c
meat and fish
acidic environment
what is iron absorption inhibited by
tannins e.g tea
phytates- cereals, bran nuts and seeds
calcium e.g dairy produce
what does cyctochrome b do to iron
reduces feric iron 3+ to ferrous form 2+
role of DMT- divalent metal transporter
transports ferrous iron into duodenal enterocyte
ferroportin role
facilitates ironn export from enterocyte
passed onto transferrin for transport elsehwere
where is ferroportin highly expressed
on basolateral membrane of enterocytes in duodenum where it transports dietary iron absorbed in intestines into bloodstream
how is iron absorption regulted
via hepcidin- mjaor negative regulator of iron uptake
where is hepcidin produced
in the liver in response to increased iron load and inflammation
MOA of hepcidin
binds to ferroportin and causes its degradation
iron therefore trapped in duodenal cells and macrophages
when do hepcidin levels decrease
when iron deficient
characterisation of iron
functional iron - hb conc
transport iron/ iron supply to tissues- 5 saturation of transfer with iron
storage iron- serum ferritin
what is transferrin
a protein with two binding sites for iron atoms
role of transferrin
transports iron from donor tissues to tissues expressing transferrin receptors
what is especially rich in transferrin
erythroid marrow
what measures iron supply
transferrin saturation
when also does ferritin go up
with infecti9on, maligancy etc as it is an acute phae protein
ferritin
protein which stores and releases iron in the body
spherical intracellular protein stores up to 4000 ferric ions
how much iron do we need
4g
consequences of negative iron balance
Exhaustion of iron stores
Iron deficient erythropoiesis
Falling red cell MCV
Microcytic Anaemia
Epithelial changes
skin
Koilonychia
Angular stomatitis
what is sideroblastic anaemia
excess iron build up in mitochondria (blue granules around nucleus) due to failure to incorporate iron in to haem. Can be hereditary or acquired eg MDS, lead poisoning, alcohol excess
how can iron def be confirmed
combo of anaemia - decreased haemoglobin iron and reduced storage iron- low serum ferritin
causes of iron overload
Primary
Hereditary haemochromatosis
Secondary
Transfusional
Iron loading anaemias
hereditary haemochromatosis
Commonest form is due to mutations in HFE gene
Decreases synthesis of hepcidin
Increased iron absorption
Results in gradual iron accumulation with risk of end-organ damage
iron build up in liver
clinical features of hereditary haemochromatosis
Weakness/fatigue
Joint pains
Impotence
Arthritis
Cirrhosis
Diabetes
Cardiomyopathy
treatment for hereditary haemochtomatosis
weekly venesection
what might patientd with thalassaemias require
lifelong transfusion
treatment of secindary iron overload
Iron chelating agents:
Desferrioxamine (subcut or IV infusion)
Newer oral agents
Deferiprone
Deferasirox
